The present invention relates to a failure diagnosis system for a vehicle, which detects failures of various devices or apparatuses installed in a vehicle and which displays an indication of the failures.
A failure diagnosis system for a vehicle has been proposed, which detects failures of various devices or apparatuses installed in the vehicle, stores the failure information in non-volatile storage elements or the like and displays the failure information for use in future checking or repair of the vehicle. All parts of a vehicle which fail are displayed by the conventional system so that they can be repaired. Such a system enables the safety and riding comfort of the vehicle to be maintained.
However, in the previously proposed system, as failure information is stored in the non-volatile storage elements, parts which fail are continuously displayed as having failed even after the parts are repaired. Thus the problem arises that devices or apparatuses which are functioning properly are checked again or exchanged if the stored failure information is not eliminated after the parts which have failed have been repaired. To solve this problem, for example, a system has been proposed in Japan Patent Laid-open Bulletins No. Sho-56-34540, which eliminates the failure information from the non-volatile elements unless a signal showing that a device is out of order is detected again within a fixed time.
However, the above-mentioned system is ineffective because it still has the following problems. In the above-mentioned system, it is difficult to determine the fixed time for eliminating the failure information. Certain types of failure are known to occur in various situations. For example, certain devices malfunction only under specified use conditions. Another type of device always malfunctions because of broken wires or the like. Consequently, if all of the failure information stored in the elements is eliminated when failure is not detected for a fixed time, there is a possibility that even information concerning failed parts which have not been repaired is not displayed. This reduces the usefulness of the failure diagnosis system. On the other hand, if the fixed time is long enough to avoid the problem, the information regarding the failed parts which have already been repaired is continuously displayed so that the problem is not solved. Thus a rule of thumb concerning the fixed time does not solve the problem.
Furthermore, in the system which executes only a one-sided display, data which is necessary for repairing can not be selected resulting in a failure to provide sufficient servicing. For example, when a device frequently breaks, there may be a specific problem in the surroundings of the device. In this case, if all of the stored failure information is eliminated after a fixed time has elapsed, the useful information is also eliminated so that the parts which have failed are not completely but only temporarily repaired.